1. Field of the Invention:
The invention pertains to high frequency field effect transistors and particularly GaAs self-aligned gate field transistors.
2. Description of the Prior Art:
A device of the prior art, which may be produced by known techniques, is illustrated in FIG. 1. The prior art device 10 comprises a GaAs substrate 12, an N-type GaAs region 14 disposed on surface 13 of the substrate 12, and a gate electrode 30 disposed on surface 15 of region 14 between source electrode 22 and drain electrode 24 as shown. Gate electrode 30 is produced by a known metallization process. The metallization of gate electrode 30 also results in the deposition of additional metal layers 26 and 28, which are disposed on electrodes 22 and 24 respectively.
It has been found that a relatively high contact resistance exists between the electrodes 22 and 24 and region 14. It is desirable to have relatively low contact resistance in order to achieve a higher gain and a correspondingly higher cut-off frequency and higher power output capability. The present invention achieves this purpose and provides other advantages which will be apparant to those skilled in the art from the description of the invention which follows.